Molecular particles keep sinking down
If your particle spheres are sinking through the floor to the center of the particle Sphere, it would indicate that you forgot to check the 'Size Deflect' check box in the Particle's Physics panel.

Also, you need to check the  'Activate Self Collision' check box in the Collision panel and adjust the friction and damping settings for the Molecular add-on to take the individual particle spheres into account when they collide against one another.

Here's a blend file in case you need it: